Cleaning oily hard surfaces



United States Patent CLEANING OILY HARD SURFACES Arthur J. Freedman,Chicago Heights, 111., assignor to Standard Oil Company, Chicago, 111.,a corporation of Indiana No Drawing. Filed Feb. 18, 1957, Ser. No.640,615 9 Claims. (11. 134-22 This invention relates to the removal ofadhering hydrocarbon oils from hard surfaces by washing with an aqueousdetergent solution.

Hydrocarbon oils adhere firmly to hard surfaces such as metals, glassand ceramic and can be removed only with difficulty. The problem is ofparticular importance in the petroleum transportation field wherein itis necessary to clean a container of the adhering oil from a previoususe before the container can be used for another oil. The problem issufficiently serious that it is common practice to designate tanks andtanker vessels for a particular type of hydrocarbon. It is common tospeak of clean oil vessels which transport things such as gasoline,kerosene, diesel fuel and heater oil and other vessels as dirty vesselsbecaue they transport crude, industrial and bunker fuel oils, reducedcrudes and asphalts. Even in the particular category of clean oils caremust be taken in introducing certain oils into oily compartments. It isundesirable to introduce kerosene into a compartment containing residualgasoline because the flash point of the kerosene would be ruined.

It is standard procedure in the petroleum transportation industry toremove hydrocarbon oils from hard surfaces by directing or impinging astream of water at elevated temperature and pressure against the oilysurface. The scouring action of the stream operating for a suflicientperiod of time removes the adhering oil. A particular procedureinvolving the use of a rotating nozzle which is lowered into the tankercompartment is universal for the cleaning of adhering oil from the metalsurfaces of tanker compartments. This procedure is commonly known asButterworthing, and is described in suificient detail in US. Patent No.2,550,997 and the particular nozzles now favored are described in US.Patent No. 2,078,566. The Butterworthing procedure has the greatdrawback that a considerable period of time is required for the cleaningof particular tanker compartments. Delays caused by the need of cleaningof compartments result in economic losses and the industry is searchingfor better ways of removing adhering oil from hard surfaces.

An object of the invention is a method of removing adhering hydrocarbonoils from hard surfaces by the use of aqueous solution. A particularobject is a method of cleaning adhering oil from tanker compartments ina shorter time than by conventional Butterworthing. Other objects becomeapparent in the course of the detailed de scription.

Briefly, the method of the invention removes hydrocarbon oils from hardsurfaces by forcibly impinging on said oily surface an aqueous liquidstream. This liquid stream contains a minor amount of a detergent whichdetergent may be either the condensation reaction product of analkylphenol and ethylene oxide or the condensation product of tall oiliwth ethylene oxide. The alkylphenol contains from 6 to 12 carbon atomsin the alkyl group and the reaction product contains from 6 to 12ethylene oxide molecules. The tall oil reaction product contains fromabout 12 to 18 ethylene oxide molecules. The aqueous stream is directedat the hard surface at a pres-sure of between about and 300 p.s.i.g. ata temperature of between about and 200 F. After the adhering oil hasbeen removed the hard surface may be freed of detergent containingaqueous solution by washing with water which does not contain anydetergent.

The hard surface is cleaned of adhering oil by the use of a liquidstream consisting essentially of water and a minor amount of a non-ionicdetergent. In general, the amount of detergent is between about 0.05 and0.25 weight percent based on water; in general, 0.15 percent issufiicient for most oils. In addition to the detergent the liquid streammay contain corrosion inhibitor such as sodium nitrite, and the variousimpurities which are present in fresh water. Sea water may be utilizedin the invention although potable fresh water is preferred.

Very large amounts of water are needed to clean tanker compartments andthis water must be disposed of. De tergents not only remove oil fromhard surfaces but they tend to form a more or less stable emulsion ofthe removed oil and the water used to remove the oil. When a tanker ispresent in a harbor or on an inland water way pollution laws preventsimple dumping of the water and oil overboard. Even on the open seas itis not considered good practice to simply dump oily Water overboard. Itis essential that the detergents be effective enough to remove theadhering oil and simultaneously permit ready separation of removed oilfrom the water by simple settling. It has been found that this verydesirable combination of eflicient cleaning and easy separation isattained with non-ionic detergents selected from the class consisting of(a) the condensation reaction product of an alkylphenol, having from 6to 12 carbon atoms in the alkyl group, with from 6 to 12 moles ofethylene oxide per mole of said phenol (b) the condensation reactionproduct of tall oil with from 12 to 18 moles of ethylene oxide per moleof said oil.

The cleansing action is obtained by forcibly impinging thedetergent-containing water stream on the oily surface at a streamtemperature between about 140 F. and 200 F. It is preferred to operateat a temperature between about F. and 200 F., particularly when removingdirty oil such as crude oil, bunker fuel oil or asphalt. The liquidstream is forcibly impinged or directed on the oily surface at adischarge pressure between about 100 and 300 p.s.i. gauge. There is somerelationship between the rapidity of oil removal and the combination ofstream temperature and pressure. Fastest removal is obtained at thehigher temperatures combined with higher pressures.

For many oils the compartment may be used even though the hard surfacedoes contain adhering detergentcontaining solution. The adheringsolution may be readily removed from the hard surface by washing withwater which does not contain detergent preferably using water at aboutthe same temperature and pressure as used in the oil removing step.

The invention is illustrated by the following working examples carriedout aboard a tanker operating on the Great Lakes. This tanker isutilized in crude oil service and in clean oil service as required bysales and refinery demands. The tanker is cleaned by Butterworthingusing fresh water at about F. and 190 p.s.i.g. The Butterworthing iscarried out while the tanker is tied to the dock using heat exchangersaboard ship and other equipment positioned on the dock. TheButterworthing operation is carried out by lowering a set of rotatingnozzles connected to the water line through the ullage hole provided ineach compartment. The nozzles are operated for about 2 hours in threepositions within the compartment, namely, just above the bottom, aboutthe mid position vertically and near the top. In order to Butterworththe remainder of the line to the nozzles. testing it was found that withthese particular detergents it was possible to completely remove theadhering crude oil clean the entire vessel using fresh water at thesecondi- In this test the vessel was cleaned with water at about 2190 F.temperature at'the nozzle and about 190 p.s.i.g.

at the nozzle. In the test 0.10 volume percent of 'various liquidnon-ionic detergents was introduced into the water. In the test thefresh water was preheated to the desired temperature and the liquiddetergent introduced into the hot water line by a pump just before thewater stream passed into the tanker compartment and down through Aftersome from the metal surfaces in the compartment in a total of two hoursand the nozzles needed to be shifted only twice, i.e., the nozzle waspositioned near the top and bottom during the cleaning period, with themid-position omitted. The detergent solution was removed from the metalsurfaces washing with fresh water only for minutes with the nozzlespositioned at about the mid-vertical point .of the compartment.

The entire vessel was cleaned by the use of these detergents in a periodof 24 hours as compared to the about 3 days by ordinary Butterworthingwithout detergent solution. In one instance the vessel was cleaned in 2days using comparatively cool water because hot water was not available;under these conditions ordinary Butterworthing would not have been ableto clean the hard surfaces at all.

The detergents used in these tests were (1) a commercial product made bycondensing diisobutylphenol with between 9 and moles of ethylene oxideper mole of said phenol (2) a commercial product made by condensingp-n-nonylphenol with 10 moles of ethylene oxide per mole of phenol, (3)a commercial product made by condensing octylphenol and 7-8 moles ofethylene oxide per mole of said phenol, and (4) a commercial productmade by condensing tall oil with moles of ethylene oxide per mole ofsaid oil. (About one 50 gallon drum of detergent was required in eachinstance to clean the entire vessel.)

The water which had been used to remove the oil was taken from thevessel to a tank ashore where it was settled with continuous withdrawalof oil layerand aqueous layerthe averaged settling time was about 2hours. In the case of the tests using detergents (1) and (2) describedabove, respectively, a moderate amount of oil was emulsified in theaqueous phase and in the case of deter- .gents (3) and (4) describedabove the oil content of the aqueous phase was slight.

In all cases the amount of oil was so low that the aqueous phase couldbe dumped into the ship channel without fear of pollution.

TEST 2 moved. This procedure was carried out three times in order tosimulate the oil-ballast cycle on the vessel. The metal strips were thenremoved from the bottle and fastened in a rack and sprayed for 5 secondson each side .with -a stream from a commercial spray gun. The eifective-.ness of the detergent in each case was determined from the degree ofwater wetting of the steel surface after cleaning.

The cleaning operation was carried out at a Water temperature of 150 F.

The emulsification power of thedetergent was determined by introducing200 ml. of potable water and deter- 4 gent into a wide mouth pint bottleand 2 ml. of crude oil; the bottle was shaken violently for 30 seconds.The tests were carried out with water'at 180 F. The oil-to-water ratioused was comparable to the ratio found in water samples taken from thedischarge line from the vessel during a normal Butterworthing cleaningoperation. The degree of separation of the oil and water phases aftercessation of the shaking was observed, as well as the color of the waterphase, and these compared with a blank wherein the water contained nodetergent. The amount of oil remaining in the water phase after 4 hoursof standing is found to be a satisfactory measure of the emulsificationpower of the particular detergent. The degree of emulsification wasnoted as severe, moderate, or slight. The amount of emulsification atmoderate or slight degrees is such that the water can be disposed intoplaces where normal sewage or waste may be disposed of without pollutionproblems.

A blank run'was made with water containing no detergent, in both thecleaning test and the emulsification test the cleaning power was poor,however, the water phase a after settling contained no oil. In all testscommercially available detergents were used. The results of theselaboratory tests are set out in Table 1 below.

Table 1 Detergent Cleaning Emulsifica- Power tion Degree Nrmp Poor-None. Diisobutylpheuol with 9-10 ethylene Exce1lent Moderate.

oxide groups. Dioctyl sodium sulfosuccinate do Severe. Nonylphenol with12 ethylene oxide do Moderate.

groups. Polyethylene glycol ether of o'ctylphenol. do Severe.Nonyllpheuol with-10 moles of ethylene do Moderate.

0x1 e. Talloilwith 15 moles of ethylene oxide do Slight. octyllphenolwith 7-8 moles of ethylene do Do.

on e.

In all the tests the detergent was present in the aqueous .solution inthe amount of Olpercent.

The above results show that all detergents do not produce the neededcombination of excellent cleaning power and low emulsification degree.The class of detergents used in the invention herein possess to aneminently suitable degree both these more or less contrary abilities.

Thus having described the invention, what is claimed is: l. A method ofcleaning a tanker compartment to remove hydrocarbon oil adhering to thewalls of said compartment, which method comprises washing the surfacesin said compartment with an aqueous solution directed against saidsurfaces at a discharge pressure of between about and 300 p.s.i.g. andat a discharge temperature between about F. and 200 'F., for a timesufficient to remove essentially all of said adhering oil, said aqueoussolution consisting essentially of water and between about 0.05 and 0.25percent of a non-ionic detergent selected from the class consisting (i)the condensation reaction product of tall oil and 15 moles of ethyleneoxide per mole of said oil, (ii) the condensation product ofdiisobutylphenol and 9-10 moles of ethylene oxide per -mole of saidphenol, and (iii) octylphenol with 7-8 moles .of ethylene oxide per moleof said phenol.

4.'The method of claim 1 wherein said detergent is octylphenol with 7-8moles of ethylene oxide per mole of said phenol.

5. The method of claim 1 wherein said temperature is between about 170F. and 200 F.

6. The process of claim 1 wherein said oil is crude oil.

7. The process of claim 1 wherein said oil is bunker fuel oil.

8. The process of claim 1 wherein said oil is kerosene.

9. The process of claim 1 wherein the oil-solution is passed to asettling zone wherein said solution is maintained for an averaged timeof at least about 2 hours and an oil layer is separated from an aqueousphase which phase is disposable into bodies of water without pollutionhazard.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Canada May 14, 1957 UNITED STATES PATENT OFFICECERTIFICATION OF CORRECTION Patent No.. 2,952,571

September 13 1960 Arthur J. Freedman It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 4, line 47, after Yless contrary abilities."- insert thefollowing paragraph:

Wherever the words "Butterworth or "Bu'tterworthing appear they are tobe understood as used in the sense of 'Butterworth tank cleaningprocedure.

Signed and sealed this 15th day of August 1961.

(SEAL) Attest:

ERNEST Wa SWIDER DAVID L LADD Attesting Officer Commissioner of Patents

1. A METHOD OF CLEANING A TANKER COMPARTMENT TO REMOVE HYDROCARBON OILADHERING TO THE WALLS OF SAID COMPARTMENT, WHICH METHOD COMPRISESWASHING THE SURFACES IN SAID COMPARTMENT WITH AN AQUEOUS SOLUTIONDIRECTED AGAINST SAID SURFACES AT A DISCHARGE PRESSURE OF BETWEEN ABOUT100 AND 300 P.S.I.G. AND AT A DISCHARGE TEMPERATURE BETWEEN ABOUT 140*F.AND 200*F., FOR A TIME SUFFICIENT TO REMOVE ESSENTIALLY ALL OF SAIDADHERING OIL, SAID AQUEOUS SOLUTION CONSISTING ESSENTIALLY OF WATER ANDBETWEEN ABOUT 0.05 AND 0.25 PERCENT OF A NON-IONIC DETERGENT SELECTEDFROM THE CLASS CONSISTING (I) THE CONDENSATION REACTION PRODUCT OF TALLOIL AND 15 MOLES OF ETHYLENE OXIDE PER MOLE OF SAID OIL, (II) THECONDENSATION PRODUCT OF DIISOBUTYLPHENOL, AND 9-10 MOLES OF ETHYLENEOXIDE PER MOLE OF SAID PHENOL, AND (III) OXTYLPHENOL WITH 7-8 MOLES OFETHYLENE OXIDE PER MOLE OF SAID PHENOL AND REMOVING ADHERING AQUEOUSSOLUTION FROM SAID SURFACE BY RINSING WITH WATER, FREE OF DETERGENT.